Polyurethane based hot melt adhesive

Abstract

Hot melt adhesive including a randomly hydroxyl functionalized branched olefin copolymer has: number average molecular weight between 10 to 50 kg/mol, crystallinity content below 30%, enthalpy between 5 to 65 J/g, polydispersity index from 2 to 6, melting temperature between 40 and 120° C., optionally, more than two hydroxyl functionalities per polymer chain and consisting of at least 80 mol % of a unit of formula (1), optionally a unit of formula (2), and between 0.1 to 1 mol %, of a unit of formula (3):wherein:R1 is H or CH3; R2 is a C0-10 hydrocarbyl group; R3 is a C2-10 hydrocarbyl group, and the hydroxyl functionalized olefin copolymer has undergone an addition reaction with a di-, tri-or polyisocyanates of formula (4):O═C═N—R4N═C═O)nWherein, R4 is a C1-10 hydrocarbyl group.

1 . A polyurethane based hot melt adhesive comprising a randomly hydroxyl functionalized branched olefin copolymer having:
 a number average molecular weight (M n ) between 10 to 50 kg/mol, measured according to the ISO 16014-4 and ASTM D6474 methods at 150° C. on a Polymer Char GPC-IR® built around an Agilent GC oven model 7890   an enthalpy (ΔH) between 5 to 65 J/g, measured according to ISO 11357-1:2016 using a Differential Scanning Calorimeter Q100 from TA Instruments,   a polydispersity index (PDI) from 2 to 6, measured according to the method ISO 16014-4 and ASTM D6474 methods at 150° C. on a Polymer Char GPC-IR built around an Agilent GC oven model 7890,   a melting temperature (T m ) between 40 and 120° C., measured according to ISO 11357-1:2016 using a Differential Scanning Calorimeter Q100 from TA Instruments,   at least two or more hydroxyl functionalities per polymer chain, and   
       wherein the randomly hydroxyl functionalized branched olefin copolymer is at least partly crystalline and has a crystallinity (X c ) level below 40% and above 1%, measured according to ISO 11357-1:2016 using a Differential Scanning Calorimeter Q100 from TA Instruments, and 
       wherein the randomly hydroxyl functionalized branched olefin copolymer consists of:
 at least 80 mol % of a constituent unit represented by the following formula (1), 
 optionally a constituent unit represented by the following formula (2), and 
 between 0.1 to 1 mol %, of a constituent unit represented by the following formula (3): 
 
       
         
           
           
               
               
           
         
         wherein:
 R 1  is H or CH 3 , 
 R 2  is a hydrocarbyl group having 0 to 10 carbon atoms, 
 R 3  is a hydrocarbyl group having 2 to 10 carbon atoms, 
 
       
       and wherein the hydroxyl functionalized olefin copolymer has been undergone an addition reaction with a di-, tri-or poly-isocyanates represented by the following formula (4):
   O═C═N—R 4   N═C═O) n  
 
 
       wherein:
 R 4  is hydrocarbyl group having 1 to 10 carbon atoms, and. 
 n is 1 to 4. 
 
     
     
         2 . The polyurethane based hot melt adhesive according to  claim 1  wherein the constituent unit represented by the formula (3) is selected from the group consisting of 3-buten-1-ol, 3-buten-2-ol, 5-hexen-1-ol, 5-hexene-1,2-diol, 7-octen-1-ol, 7-octen-1,2-diol, 5-norbornene-2-methanol, and 10-undecen-1-ol. 
     
     
         3 . The polyurethane based hot melt adhesive according to  claim 1 , wherein the polymerization has been performed using a solution process. 
     
     
         4 . The polyurethane based hot melt adhesive according to  claim 3 , wherein a purification step consisting of removing traces of inorganic impurities, which remain in the resin after polymerization, has been performed prior the addition reaction. 
     
     
         5 . The polyurethane-based hot melt adhesive according to  claim 1 , comprising the following cross-linked system 
       
         
           
           
               
               
           
         
       
       wherein
 z, z′ is 0.1 to 1 mol %, 
 x, x′ is at least 80 mol %, 
 y is 0 or 100−(x+z) mol %, and y′ is 0 or 100−(x′+z′) mol %, 
 R 1  is H or CH 3 , 
 R 2  is a hydrocarbyl group having 0 to 10 carbon atoms, 
 R 3  is a hydrocarbyl group having 2 to 10 carbon atoms, 
 R 4  is hydrocarbyl group having 1 to 10 carbon atoms, and 
 n is 1 to 4. 
 
     
     
         6 . A method comprising: applying the polyurethane based hot melt adhesive according to  claim 1  to glue together metals, glass, polar polymers or metals to glass, metal to polar polymers, glass to polar polymers, metals to polyolefins, glass to polyolefins or polar polymers to polyolefins. 
     
     
         7 . The polyurethane based hot melt adhesive according to  claim 1 , having at least one of the following binding properties measured according to the ASTM D1002-10(2019) with a Zwick type Z020 tensile tester equipped with a 10 kN load cell:
 steel to steel with a Lap Shear Strength above 3 MPa,   aluminum to aluminum with a Lap Shear Strength above 3 MPa, or   polyolefin to polyolefin with a Lap Shear Strength above 3 MPa.   
     
     
         8 . The polyurethane based hot melt adhesive according to  claim 1 , having a storage modulus (E′) at 20° C. above 115 MPa, and at −40° C. above 2030 MPa, measured according to the method described in the section Dynamic Mechanical Thermal Analysis (DMTA) of the present application, and a Loss modulus (E″) at 20° C. above 17 MPa and at −40° C. above 36 MPa measured according to Dynamic Mechanical Thermal Analysis (DMTA).